They may look fine on the outside but if your's are falling after they come out of the oven it means most likely they are just not cooked enough inside. You need to leave them in the oven longer in order to dry out the inside. Maybe at a lower temp so as to not burn them . Sometimes you can just leave a wooden spoon in the door to keep it ajar.
Some will just leave them in the oven for an extra 1/2 hr with the oven shut off... Once the inside is fully cooked and dry it will no longer collapse.. If you experience color problems when baking just cut back a little on the butter and use more shortening in your formula and also cut back on any sugar you might be adding to the batter. The only other thing that could cause a problem for you would be that you have too many eggs in your batter to start with and it ends up too thin......
If you cook them properly you shouldn't have to do any thing with them except fill them. Foodi
foodi4lif has good advice. You can add more egg whites to your paste to get a crispier texture. In place of whole eggs, that is. I like to use a knife or toothpick to poke a hole in the side after most of the cooking is done and put them back in the oven to really dry the puffs out.
I tried the method suggested by poking the bottom section of the puff with a toothpick and then putting back into the oven for another half hour. It works beautifully.